From: Daniel Vetter Date: Fri, 2 Oct 2015 11:01:02 +0000 (+0200) Subject: drm/sysfs: Grab lock for edid/modes_show X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a48a62bc9226e731e2284afb1c782869a413e1b2;p=linux-beck.git drm/sysfs: Grab lock for edid/modes_show We chase pointers/lists without taking the locks protecting them, which isn't that good. Fix it. v2: Actually unlock properly, spotted by Julia. v3: Put the label _before_ the mutex_unlock (Emil) Cc: Emil Velikov Cc: Julia Lawall Link: http://patchwork.freedesktop.org/patch/msgid/1443783662-23066-1-git-send-email-daniel.vetter@ffwll.ch Reviewed-by: Emil Velikov Signed-off-by: Daniel Vetter --- diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c index 615b7e667320..c75f02297d01 100644 --- a/drivers/gpu/drm/drm_sysfs.c +++ b/drivers/gpu/drm/drm_sysfs.c @@ -256,23 +256,29 @@ static ssize_t edid_show(struct file *filp, struct kobject *kobj, struct drm_connector *connector = to_drm_connector(connector_dev); unsigned char *edid; size_t size; + ssize_t ret = 0; + mutex_lock(&connector->dev->mode_config.mutex); if (!connector->edid_blob_ptr) - return 0; + goto unlock; edid = connector->edid_blob_ptr->data; size = connector->edid_blob_ptr->length; if (!edid) - return 0; + goto unlock; if (off >= size) - return 0; + goto unlock; if (off + count > size) count = size - off; memcpy(buf, edid + off, count); - return count; + ret = count; +unlock: + mutex_unlock(&connector->dev->mode_config.mutex); + + return ret; } static ssize_t modes_show(struct device *device, @@ -283,10 +289,12 @@ static ssize_t modes_show(struct device *device, struct drm_display_mode *mode; int written = 0; + mutex_lock(&connector->dev->mode_config.mutex); list_for_each_entry(mode, &connector->modes, head) { written += snprintf(buf + written, PAGE_SIZE - written, "%s\n", mode->name); } + mutex_unlock(&connector->dev->mode_config.mutex); return written; }